The Statistical/Computing Core is an indispensable component of the San Antonio STI TM CRC proposal, providing the data collection and organizational backbone for all physical examinations, clinical questionnaires, behavioral questionnaires, and laboratory assays, as well as all study clinic activities, including subject/dyad tracking and required reporting to health departments. Members of the Statistics/Computing Core will ensure the continued integrity of the Research Projects by overseeing data collection and ensuring the proper linkage of the various components of the STI TM CRC. These tasks will be accomplished through the use of a customized multi-functional database developed and maintained by Core personnel. In addition, the Statistical/Computing Core will provide expertise in computer hardware and software, including maintaining and upgrading all computer systems encompassed within the STI TM CRC. Finally, after data have been collected, members of the Statistical/Computing Core, with expertise in epidemiologic study design, statistical analysis techniques, and computer programming, will provide a central support system for all data analysis and interpretation activities undertaken by the Research Projects comprising the STI TM CRC, and will implement appropriate analytic methods for collaboratively addressing all Project Aims that involve statistical data analysis. Members of the Statistical/Computing Core will be closely integrated with each Project, providing specimen tracking and identification, as well as linkage of specimens across time within patients and dyads. Data collected at each visit for the Behavioral Project will be linked to results obtained from the Microbiology Research Projects and the Clinical Project in order to correlate laboratory findings with concurrent clinical, behavioral, situational, and other characteristics of the subjects. For the Behavioral Project in particular, Statistical/Computing Core personnel will be integrally involved at every step of the data analysis, including the assessment of intervention impact, the development of complex variable constructs, and the examination of numerous research questions relating to the understanding and prevention of STI transmission.